We propose to develop methodology for detecting and concentrating hepatitis virus type A (HAV) and human rotavirus (infantile gastroenteritis virus) from potable water, sewage and shellfish. In preliminary work we have demonstrated that HAV and rota-virus can be concentrated from water and/or sewage by adsorption-elution from membrane filters. We propose to further develop and optimize this method or alternate methods for the concentration of these viruses from large volumes of water and wastewater. Because initial experiments can be performed on a micro-scale, more than sufficient antigen is available to complete these studies. Viral assays will be accomplished by adapting a microtiter solid-phase radioimmune assay (RIA) or enzyme linked immunoadsorbent assay (ELISA) for the detection of HAV and human rotavirus in water and shellfish concentrates. Methods we have developed recently involving ultrafiltration or alternate methods for the efficient concentration of enterovirus from large numbers of shellfish will be optimized for the detection of HAV and human rotavirus. The methods will then be used in the field to determine the prevalence of HAV and the agents of viral gastroenteritis in sewage and shellfish.